Often, we have an opportunity to take a spontaneous photograph of a friend outdoors, on a bright sunny day. If the sun is high up in the sky, it's easy to end up with a picture where the person's eyes are in deep shadow, and they are squinting.
When a situation like that arises, it's time to look around for open shade. Maybe there is a tree close by that you can put the person under, or a doorway they can stand in. Or maybe there is an overhang on a building.
Whatever the options, look for opportunities to get your subject out of the harsh, overhead light, and into open shade. The results will certainly be worth the extra effort.
For more detailed information and additional examples from this shoot, and other tips on how to improve your photography, visit Allen's photoblog at A Better Photograph.com.